When a mobile device is directed by the network to perform a hard handover from one cell to another, it must quickly obtain the timing of the target handover cell so that user traffic can be reestablished. A number of circumstances can make inter-frequency hard handover necessary. For example, hot-spot scenarios are where a cell uses more carriers than the surrounding cells. For another example, hierarchical cell structures are where macro, micro, and pico layers are on different frequencies. For an additional example, a handover can be made between different operators. For a further example, a handover can be made between different radio access technologies systems (e.g., UMTS TDD, UMTS FDD, and GSM).
The target handover cell is specified by its frequency and Primary Scrambling Code (PSC). Typically, this is accomplished by first searching the Primary Synchronization Channel (P-SCH) to detect slot-level timing, then using the slot timing hypothesis and specified PSC to detect the Common Pilot Channel (CPICH) over a relatively small search window. The search window can be smaller for CPICH because of the P-SCH detected timing. In many network configurations, the P-SCH channel power level is significantly weaker than the CPICH. In challenging channel conditions, it may be extremely difficult for the mobile to detect the P-SCH channel. The invention improves hard handover performance in challenging channel conditions by dynamically switching between traditional and advanced timing acquisition techniques when the first attempt to obtain cell timing has failed.